Telephone system



Nam 8, QE

H. L. HOFFMANN TELEPHONE SYSTEM Filed May 5. 1924 www . Fdwm scribers line.

each B operator is assigned to attend to a Patented Nev. 8, 1927.

entre stares l9647,9il3

t' l? i C E y HENRY L. HOFFMANN, OF EAST GRANGE, NEW JERSEY, ASSIGNOR TO WESTERN ELC- TRIC CQLIPANY, INCORPORATED,` OF LIEVJ YORK, N. Y., A CGRPORATION OF YORK.

Application led May 5,

This invention `relates to telephone exchange systems and more particularly to improvements in trunk circuits i'or establishing connections between .nianual e3;- changes.

The invention is adapted for use in systems in which calls received at one manual exchange are extended by means of so-called A operators cord circuits and trunk 4lines terminating in plugs at a so-called B operators position located in another exchange where this latter operator may complete the connection by inserting the plug ci a. seized trunl: line into the jack. ot a wanted sub- Ordinarily in such systems,

number ot' incoming trunk lines and her telephone rset is manually connected to an`\7 seized trunk line by the operation of a lrey. The trunk line to be used in each instance is usually assigned by the B operator by means ot a. separate call wire circuit extending between the operators in the two exchanges. In certain types of trunk systems, however, this call wire service is dispensed with by having the A operator seize any one of the trunks leading to the desiredB operators position where means isprovi ded for identit'ying the seized trunk. f

`Systems of this type are usually called straight forward trunking systems and it is an object of this invention to provide a. greatly simpliiied system of this type in which the A operator may seize any available trunk leading to the desired exchange from which the wanted subscriber may be reached and whereby the B operator in such an exchange is automatically connected to a trunk line 'the moment it is seized and disconnected therefrom the moment she extends the connection to the wanted subscribers line.

.Another object.` is the provision ot an arrangement whereby the manner oi" operating the usual signaling apparatus required tor the proper supervision of the c all is greatly simplitied. I s

These objects are obtained in accordance with one feature of the invention by the use ot a switch and relay arrangement operated the moment a trunk is seized to automatically connect the B operators telephone set thereto.

Another feature is the provision ot a greatly simplilied circuit` for telephonically "in a jack 18 at this exchange.

TELEPHONE SYSTEM.

1924. Serial No. 711,941.

completing the connection between a seized trunk and the B cperators telephone set.

Another feature is the provision of av relay arrangement whereby the B operators telephone set is disconnected from a seized trunk the momentit is extended beyond without further operation of the switch. l

Another feature isthe provision in connection with each trunk of a signal and operating means therefor whereby said signal is operated in one manner to indicate tothe B operator that this particular trunk has been seized and in a different manner that her telephone set has been connected thereto.

Another feature is the provision of means in the trunk whereby one signal indication is given when the A operator disconnectsher cord circuit from a. seized and extended trunk line and another signal indication if she again connects with this trunk 'linebetore the B operator has disconnected it trom the previously called subscriber.

Another feature is the provision of means whereby the ringing equipment used in trunks of this type is prevented fromoperating to rer-ing the previously called subscriber if the A operator attempts to establish a new connection over this engaged trunk.

, Referring now to the drawing in which one embodiment of the invention is illustrated, there is shown onthe left of the dotted vertical line a calling subscriber 10, whose line terminates in a jack 11 at the manual switchboard, an A operators cord circuit A. and a jack 16 of a trunk T outgoing to ani' other exchange. On the right of this vertical line is shown the incoming end ofthe trunk T terminating in a plug 17 and a wanted subscriber 2O whose line terminates dotted line is shown a B operators telephone set and associated equipment tor automatically connecting her set to any one of a group of trunks such as T position.

In order to obtain a clear understanding; ot' the invention illustrated, a description will be given of the functions involved in the sett-ing up of a connection from suby scriber 10 to subscriber 20. The callingv subscriber 10 is connected by means of jack 11 and answering plug 12 to the A operators cord circuit A and to her telephone set AOT by means oi the usual listening` key as isterminating at herKA Below the Well-known in the art and the details of this connection need not therefore be further described. The A operator after haring received from subscriber 10 the number of the wantedv subscribers line inserts the calling plug 15 of cord circuit A into jack 16 of trunk T leading to the exchange through which the wanted subscriber 2() may be reached. This causes the operation of the supervisory signal 14 in the cord circuit A as follows: battery, lamp 14, sleeve contacts of plug 15 and jack 16 to ground. Another circuit is also closed to operate relay 23 of 'l` as follows: battery, lower right-hand winding of repeating coil 17 of cord circuit A, winding of supervisory relay 13, ring contacts of plug 15 and jack 16, lower left-hand winding of repeating coil 22 of trunk T, right-hand and left-hand windings of relay 23 in series, upper left-hand winding of repeating coil 22, tip contacts of jack 16 and plug 15, upper right-hand winding of re peating coil 17 to ground.

Relay 23, in operating, initiates operations resulting in the lighting of lamp 25 and the association of the B operators telephone set BOT with the trunlr T. The first circuit closes as follows: battery, lamp 25, armature and front Contact of relay 23, lower armature and back contact of relay 2a, upper winding of relay 24, resistance 26, Winding of reiay 51 to ground. Lamp 25 is lighted in this circuit to indicate to the B operator that trunk T has been seized by the A operator.

The operation of relay 51 closes a circuit for the operating magnet 52 as follows: battery, winding of operating magnet 52, armature and back contact thereof, armature and front contact of relay 51, outer armature and back contact of relay 53 to ground. The operating magnet 52 and switch 5() constitute the elements of the usual no normal position rotary step-by-step switches, well known in the art and the detail construction of this switch and magnet need not, therefore, be further described except to say that .the brushes 54 and 55 thereof are adapted to rotate one step each time magnet 52 is operated to contact with the terminals of banks 56 and 57 respectively. It will be notedv that the armature of magnet 52 will open the energizing circuit for the rmagnet each time it is attracted and the brushes 5% and 55 are therefore stepped forward in a clockwise direction until they come in contact with the terminals connected to the conductors individual to the trunk T. At this time the energizing circuit for operating magnet 52 will be broken at the outer righthand armature and back contact of relay 53 by the Closing of the following circuit: battery, lamp 25, armature and front Contact of relay 23, lower armature and back contact of relay 24, conductor 27 and the associated terminal, brush 55, left-hand winding of relay 53 to ground. The brushes 54 and 55 will, therefore, remain on their respective terminals as shown. The operation of relay 53 closes a circuit for its right-hand winding and interrupter 60 as follows: battery, 1nterrupter 60, inner right-hand armature and front contact of relay 53, right-hand winding of relay 53, left-hand winding of relay 53 to ground. `When, therefore, interrupter 60 connects battery through this path, the path from battery at lamp 25 to ground at relay 53 will be shunted and the lamp extinguished. When the battery through interrupter 60 is removed the lamp 25 will again be lighted and this lamp 25 will therefore flash in accordance with the interruptions of battery at interrupter 60. This ashing of lamp 25 indicates to the B operator that her telephone set has been connected to trunk T.

The connection of the B operators telephone set BOT to the trunk T takes place as follows: On the first operation of relay 53 the following circuit is closed: battery, winding of relay 62, armature and back contact of relay 63, outer right-hand armature and front contact of relay 53 to ground. The operation of relay 62 closes a circuit for the tone device 64.- as follows: battery, lower right-hand winding of repeating coil 22, winding of relay 31, conductor 32, and the associated terminal of switch 50, brush 5ft, upper armature and front contact of relay 62, condenser 65, right-hand winding of repeating coil 66 to ground. The tone device 64 may be of any well-known type and the induced current through this repeating coil 66 to the last mentioned circuit is transmitted through the repeating coil 22 to the A operators telephone set AOT connected t0 the tip and ring leads of the cord circuit A associated with trunk T and the operator is thereby notified that the B operators telephone set is connected or is presently to be connected and that conversation may take place. This circuit for tone device 64 is only momentarily connected through to the A operators position as the operation of rclay 62 closes an energizing circuit for relay 67 as follows: battery, right-hand winding of relay 67, lower armature and front contact of relay 62, right-hand armature and back contact of relay 63, outer right hand armature and front contact of relay 53 to ground. The operation of relay 67 closes a locking circuit for itself as follows: battery.

left-hand winding of relay 67. left-hand armature and frontl contact of relay 67. winding of relay 63, outer right-hand armature and front contact of relay 53 to ground. This locking circuit it will be noted passed through the winding of rela)v 63 which now operates opening the original energizing circuits for relays 62 and 67, and relay 62 is, therefore, released opening the circuit for the tone device 64. The release of relay 62 lll) and operation of relay 67 now completes a circuit for the B operators telephone set BOT as follows: battery, lower-right hand winding of repeating coil 22, winding of relay 31, conductor 32, brush 54, upper armature and back contact'of relay 62, right-hand armature and front contact of relay 67, condenser 68, upper right-hand winding of repeating coil 69 to ground. The B operators telephone set BOT is now inductively connected through the upper windings of repeating coil 69 to the A operators telephone set AOT as shown and conversation between these two operators may now take place.

ynumber of the wanted subscriber from the A operator inserts her plug 17 of trunk T into a jack 18 connected to the line of the wanted subscriber 20, that is to say after she has performed the usual busy test well known in the art. This connection results in the operation of relay 24, extinguishing of lamp and disconnection of the B operators telephone' set from the trunk circuit T. Relay 24 is operatedkover the following circuit:v battery, lamp 25, lower winding of relay 24, ring contacts of plug 17 and jack 18 to ground. Relay 24 in attracting its lower armature opens the circuit at the back contact thereof for relay 53. This relay 53 releases immediately or as soon as the battery is removedby interrupter GO and in releasing opens the holding circuit for relays 63 and 67. The release of relay 67 at its righthand armature and front contact opensy the above mentioned circuit and thus causesy the disconnection of the B operators telephone set.

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The operation of the lower' armature'of relay 24` closes a circuit for the application of causes at its upper armature and front con-' tact the tip conductor of the trunk T to be continued from the upper armature ot relay 28 to the tip of plug 17. The operation` of relay 28 connects ringing current to the wanted subscriber as follows: ringing source' 35, winding of ringing Vcut-olf relay 29, lower armature and frontcontact of relay 28, ring conductor of trunk T, ring contacts of plug 17 and jack 18 to the bell of the wanted subscribers telephone set, back through the tip contacts of jack 18 and plug 17, upper armature and front contact of relay 24, tip conductor of trunk T, upper armature and front contact of relay 28 to ground. i

yThe subscriber at 20 in removing' this receiver from the hook to answer Ythis `call causes ringing trip relay 29 to operate as is well known in the art and the operation of this relay opens at its armature and iront contact, the shunt circuit for the lower winding of `relay 3U, and the circuit'previously traced from battery at the winding of relay 28 to ground at the sleeve contact of jack 18 will now he closed through the lower winding of relay 30 causing this relay to operate in series with relay 28. However,

the operation of relay 30 will immediately short circuit relay 28 by the closing of a path, from battery at the lower armature and front Contact of relay 30, through the winding of relay 30 to the ground at jack 18. Relay 28 in releasing` removes the ringing source from the conductors to thevcalled subscribers line. Alocking circuit is conn rpleted for relay 3() on the operation thereof as follows: battery, upper armature and front Contact of relay 30, upper winding of A relay 30, sleeve contacts of plug 17 and jack 18 lto ground, thus makinathis relay 30 independent of the circuit iihrough the armature and front ycontact of relay 23. The release of relay 28 now extends the talling conductors of the trunk `T from the hat tery at the right-hand windings of repeating coil 22 to the wanted subscriberstelephone set as follows: battery, lower-right-hand winding of repeatingcoil 22, winding ofrelay 81, lower armature and back contactV of relay 28, ring contacts of plug 17 and jack 18, through the subscribers loop, back through the tip contacts of jack 18 and plug 17, upper armature `and front Contact of relay 24, upper armature and back contact of relay 28, Lipper' right hand winding of reeatinO coil 22 to o'round. This ycircuit causes relay 31 to operate and close at its left-hand armature and front contact a short circuit for the left-hand winding of relay 28 causing an increase current from the battery at the repeating coil 17, through the winding of supervisory relay 13. This relay 18 operates establishing a short circuit for lamp 14 at its armature and front contact as is well-known in the art, causing this lamp to be extinguished which serves as an indication to the A operator that the connection to the wanted subscriber has been completed and that conversation between the subscribers 10 and 2O may now take place.

lVhen, at the end of the conversation sub` scriber 20 hangs up his receiver the current in the circuit for relay 13 is again reduced, by the removal of the short circuit about the left hand winding of relay 28 causing this relay to release which again lights lamp 14 as an indication to the A operator that the connection may be taken down. The A operator now removes the plug lfrom jack 16 and lamp 14 is thereby extinguished and relay 23 released. Relay 23, in releasing, opens at its arn'iature and front contact the short circuit 'for lamp 25 through the lower armature and front contact ot' relay 24, winding of relay 30 to battery at its lower armature and front contact and the lamp is thereby lighted to indicate to the B operator that the A operator has disconnected. The B operator will thereby remove plug 17 from jack 18, causing relays 24 and 80 to be released and lamp y25 to be extinguished.

In case the A operator 'should again insert her plug 15 in jack 16 before the B operator had removed her plug 17 from jack 18, this second connection will be noticed by the B operator through the extinguishing of lamp 25 as relay 23 will again be energized, the short circuit for this lamp reestablished through the lower winding of relay to battery. Subscriber 2O will however not be rung a second time as relay 30 is held operated at long as plug 17 remains in jack 18 due to the locking winding established from battery at the upper armature and front contact of this relay. The B operator on noticing that lamp 25 is again dark after having first been lighted, will know that the A operator has disconnected the original calling subscriber from the trunk and is now connecting another subscriber thereto. She will then remove plug 17 from jack 18 and lamp 25 will. then be lighted to affirmatively indicate to her that the A operator has again seized the trunk and her telephone set will `be connected to this trunk T a second time as hereinbefore described.,

yShould the A operator attempt to malte connection with another trunk such as the one that would be connected through resist* ance 40 to relay 51 while the B operators telephone set is connected to trunk T, relay 51 will not operate as this relay will be shunted by the ground through the lefthand winding or relay 53.

That is claimed is:

1. A telephone system comprising trunk lines, means for seizing any one of said trunk lines at one end thereof, an operators telephone set, a switch operated when one of said trunk lines is seized for finding said trunk line, means for connecting said telephone set to said seized trunk line operative lwhen said switch has found the seized trunk line, and means for disconnecting said telephone set from said trunk line without operating said switch when the seized trunk line is extended at the opposite end.

2. A telephone system comprising trunk lines, a cord circuit, an operators telephone.

set. a switch operative when one of said trunk lines is connected to said cord for nding said trunk line, a circuit associated with said telephone set, and means for connecting said circuit to said switch operative when said, switch has found the seized trunk line.

3. A telephone system comprising trunk lines, a first operators position, means for seizing any one of said trunk lines at said first operators position, an operators telephone set at a second operator-s position, a selecting device common to said trunks associated with said telephone set, meansresponsive to the seizure ot' one of said trunk lines at the said first operators position for setting said selecting device into operation, and means operative when one of said trunk lines is seized at said first position for connecting said telephone set with said trunk line through the medium ot' said selecting device.

4. A telephone system comprising trunk lines, means :t'or seizing any one of said trunk lines, an operators telephone set, a circuit associated with said telephone set, a tone producing device, means operative when a trunk line is seized for momentarily connecting said device over a portion of said circuit to said seized trunk line, and means i'or thereafter connecting said telephone set through said circuit to said seized trunk line.

5. In a telephone system comprising trunk lines, means For seizing any one of said trunk lines at one end thereof, an operators telephone set, a circuit associated with said telephone set, a tone producing device, means operative when a trunk line is seized 'for momentarily connecting said device over a. portion of said circuit to said seized trunk line, means for thereafter connecting said telephone set through said circuit to said seized trunk line, and means for opening said circuit to disconnect said telephone set from said seized trunk line operative when said trunk line is extended at the opposite end.

6. A telephone system comprising trunk lines, means for seizing any one of said trunk lines, a signal associated with each of said trunk lines, means for operating the associated signal when the trunk line is seized, an operators telephone set, a switch operative when a trunk line is seized for inding said trunk line, means 'for connectingr the telephone set to said switch and trunk line when said switch has found the trunk line, and means for thereafter operating thc associated signal in a dii'i'erent manner.

7. A telephone system comprising trunk lines, means for seizing any one ot said trunk lines at one end thereof, a signal associated with each of said trunk lines, means i'or operating the associated signal when a trunk line is seized. an operators telephone set, means operative when a trunk line is seized ior connecting said operators telephone set thereto, means for operating said signal in a different manner when the operators telephone set is connected to the trunk, means for disconnecting said telephone set from the seized trunk when it is extended at the opposite end7 means for disabling the signal when a trunk is extended and means for again operating said signal if the seized trunk is released and for again disabling it if the trunk is again seized but still extended at the opposite end.

8. In a telephone system, the combination of trunk lines, means for seizing any one of said trunk lines at one end thereof,

means responsive to the seizure of one of said trunk lines at one end thereof for connecting a telephone set thereto, means for extending a seized trunk at the opposite end thereof to subscribers stations, means responsive to the extension of a trunk line to a subscribers station for disconnecting said telephone set from said trunk line, means automatically operable substantially simultaneously With said last mentioned means for transmitting ringing current to said subscribers station When a trunk line has been extended thereto, means for automatically discontinuing the ringing when the called subscriber answers, and means for preventing ringing signals from being again transmitted to the connected subscrbers station if the trunk line is released and again seized and for again permitting ringing signals to be transmitted if the trunk line is subsequently extended to another subscnibers station.

In Witness whereof, I hereunto subscribe my name this 28th day of April A. D., 1924.

HENRY L. HOFFMANN. 

